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<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>

    <script>
        let {
            keys,
            values,
            entries
        } = Object;

        let json = {
            a: 1,
            b: 2,
            c: 3
        };

        console.log(keys(json)); // (3) ["a", "b", "c"]
        for (let key of keys(json)) {
            console.log(key); // a  b  c
        }

        // console.log(values(json)); // (3) [1, 2, 3]
        for (let key of values(json)) {
            console.log(key); // 1  2  3
        }

        // console.log(entries(json)); // [Array(2), Array(2), Array(2)]
        for (let [key, val] of entries(json)) {
            console.log(key, val);
            // a 1   
            // b 2  
            // c 3
        }
    </script>

</body>

</html>